The present invention relates to a novel optical fiber tape that can be used advantageously in such applications as high density lightwave communications. More particularly, the present invention relates to a coated optical fiber tape furnished with a coating layer that allows easy handling in such operations as splicing and which exhibits superior resistance to lateral pressures.
With the recent advances in the technology of information communications, there has been a growing need for transmitting signals at a higher speed. One of the embodiments of such high-speed signal transmission technologies is the commercial application of lightwave communications. Besides being capable of realizing highspeed transmission by virtue of the nature of light itself, optical signal transmission not only exploits the light-weightness of optical fibers serving as lightguides but also offers distinct advantages in communications technol-ogy such as immunity to magnetic and electric fields. Notwithstanding these capabilities, conventional optical fibers as lightguides are yet to fully satisfy the requirement for transmitting a larger volume of signals and researchers are responding to this need by making various improvements of signal transmitting optical fibers.
Coated optical fiber tape is one of the applications of the techniques so far proposed under these circumstances. Coated optical fiber tape consists of an array of optical fibers serving as lightguides which are covered with a common coating layer to form a unitary assembly that has the potential to realize high-density signal transmission by simple handling.
FIG. 5 is a cross section showing the composition of a typical coated optical fiber tape. Light-transmitting optical fibers 1 individually furnished with a coating 2 are arranged side by side in tape form and provided with a common coating layer 4. In the prior art, the individual fiber coatings 2 and the common coating layer 4 are typically formed of an ultraviolet (uv) curable polyurethane acrylate resin.
In commercial operations, such coated optical fiber tape has to be spliced to other parts such as single coated optical fibers. In such instances, if the coated optical fibers to be spliced remain in tape form, problems will occur in terms of such aspects as handling and splicing loss. To solve these problems, the common coating layer 4 has to be stripped, followed by end preparation of individual fibers 1.
With a view to meeting this need, it has been proposed that a peelable cured coating layer be provided between the coatings 2 on the individual fibers 1 and the common coating layer 4 so as to prevent the common coating layer 4 from being bonded or urged to the fiber coatings 2. Coated optical fiber tapes having this construction are described in, for example, Japanese Utility Model Application No. 126584/1986.
One major problem with this type of coated optical fiber tapes is that the physical properties of the material of which the peelable cured coating layer is made have not been fully considered. As a consequence, installation of such a peelable cured coating layer often causes deterioration of the characteristics, in particular, lateral pressure resistance, of the coated optical fiber tape, and this leads to an undesired phenomenon such as increased transmission loss when a plurality of fiber tapes are assembled into a cable.